This invention relates to a crane having a foldable boom.
When a crane is mounted on a motorized carrier or the like, it is desirable to be able to selectively shorten the boom to facilitate travel of the carrier on highways. Such shortening has often been accomplished by forming the boom in two or more connectable sections, with the outer section being foldable.
In some instances, it has been found that when a lengthened outer boom section was folded for travel, its tip portion would engage and undesirably interfere with the operator's cab or other carrier structure. This limited the extent of boom lengthening unless the remaining elements were reconstructed.
The concept of the present invention is based on a solution to the above-mentioned problem and the discovery of a way to fold a lengthened crane boom section in a manner so that it will not engage the carrier structure.
In accordance with the invention, a carrier-mounted crane is provided with inner and outer boom sections which are securable together at upper and lower connections. When the outer boom is to be pivotally folded beneath the inner boom, the lower connection comprises a folding compound arm extending between the boom sections and pivotable intermediate its ends. When the upper boom connection is released and the outer boom folded under, its main pivot connection to the compound arm shifts longitudinally away from the inner boom section, thus effectively moving the outer boom away from the carrier. The tip or outer end of the folded outer boom will thereby remain free of interference with the carrier elements.